JP3116808B2 - Fail-safe control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a fail-safe control device for a continuously variable transmission, and more particularly to a hydraulic control employed in a V-belt type continuously variable transmission.

[0002]

2. Description of the Related Art As a continuously variable transmission mounted on a vehicle,
A V-belt type is conventionally known, and for example, there is JP-A-61-105347 proposed by the present applicant.

[0003] This is provided with a pair of variable pulleys on the drive side and the driven side whose contact pulley width with the V-belt of the continuously variable transmission is variably controlled based on the hydraulic pressure. The gear ratio is continuously changed by changing the size, and the contact friction force between the V-belt and the variable pulley is variably controlled according to the line pressure.
This line pressure is set according to the magnitude of the input torque,
The contact friction force between the belt and the pulley is secured according to the line pressure.

[0004] Shift control of such a continuously variable transmission includes a stepping amount of an accelerator pedal operated by a driver,
Automatic gear shifting is performed to calculate the target gear ratio according to the vehicle speed and to control the oil pressure to the variable pulley so that the actual gear ratio matches the target gear ratio. The gear is automatically shifted to the appropriate gear ratio.

The line pressure for ensuring the contact friction force between the V-belt and the pulley is supplied to the shift control unit by the duty.
It is adjusted by a controlled solenoid valve, etc.
Even if the solenoid valve becomes inoperable due to disconnection or failure of the control circuit or solenoid that constitutes the line pressure control system, the line pressure to the variable pulley is secured to prevent the V-belt from slipping and the vehicle travels. Need to be possible.

For this reason, the solenoid valve is normally
An apply type is adopted, and when electricity is cut off, the valve is opened to constitute a fail-safe means for securing the line pressure supplied to the variable pulley.

Therefore, even in the event of a failure in which the energization of the solenoid valve is cut off, the line pressure supplied to the variable pulley is ensured, enabling the vehicle to travel while preventing wear due to slippage of the V-belt and the pulley. The durability of the step transmission is ensured, and the oil temperature in the continuously variable transmission is also prevented from excessively rising due to the slip of the V-belt.

[0008]

However, in the above conventional example, when the above-described failure occurs and the solenoid valve opens when the engine speed is high,
As shown in FIG. 7, since the line pressure rises to a predetermined maximum value PLmax, the contact frictional force between the V-belt and the pulley becomes excessive, and if such an operation state continues, the oil temperature T in the continuously variable transmission becomes a limit. In some cases, the oil temperature rises above Tmax, and the durability of the continuously variable transmission is reduced.

The present invention has been made in view of the above-mentioned problems, and when a failure occurs in a line pressure control system, the V-belt can be prevented from slipping while running while preventing excessive line pressure. An object is to suppress an excessive rise in oil temperature due to the rise.

[0010]

As shown in FIG. 8, the first invention comprises a pair of variable pulleys on a primary side and a secondary side in which the contact frictional force of a V-belt is variably controlled based on line pressure. A continuously variable transmission 100, a shift control means 101 for calculating a command value of the line pressure according to a driving state of the vehicle, a hydraulic pressure from a hydraulic source based on the command value of the line pressure and a variable pulley. Safe control device for a continuously variable transmission, comprising: a line pressure control means 103 for supplying pressure to the variable pulley and a fail safe means 104 for supplying a predetermined maximum oil pressure to the variable pulley when the line pressure control means 103 fails. , An engine control means 102 for controlling an engine connected to the continuously variable transmission 100 in accordance with a driving state of the vehicle; and a means 105 for detecting the line pressure. The line pressure of the detected value and the shift control means 101 of the line pressure command value on the basis of determining failure determining means a failure of the line pressure control means 103 106
And an engine speed control means 107 for requesting the engine control means 102 to reduce the engine speed when a failure is determined in this determination, wherein the engine control means 102 receives a request from the engine speed control means. The engine speed is suppressed in accordance with.

[0011] In a second aspect based on the first aspect, the failure determination means is configured such that the line pressure command value is less than a predetermined maximum value and the detected line pressure value is greater than or equal to a predetermined maximum value. Sometimes, a failure of the line pressure control means is determined.

In a third aspect based on the first aspect, the failure determination means is configured such that the line pressure command value is less than a predetermined maximum value and the detected line pressure value is greater than or equal to a predetermined maximum value. When the state continues for a predetermined time, a failure of the line pressure control means is determined.

[0014] In a fourth aspect based on the first aspect, the engine control means is configured to perform fuel cut or fuel cut so that the engine speed is less than a predetermined value in response to a request from the engine speed suppression means. The fuel injection amount is reduced.

In a fifth aspect based on the first aspect, the engine control means reduces the maximum value of the engine speed in response to a request from the engine speed suppression means.

[0015]

According to the first aspect of the present invention, a pair of variable pulleys for holding the V-belt are connected to the V-belt in accordance with the driving state, for example, by the line pressure determined based on the vehicle speed and the accelerator pedal opening. The contact friction force of the variable pulley is set. If the line pressure control means fails, first, the fail-safe means supplies a predetermined maximum oil pressure to the variable pulley to prevent slippage of the V-belt. The running of the vehicle can be continued. At this time, since the detected value of the line pressure does not match the line pressure command value from the shift control means due to the failure, the failure determination means determines the failure of the line pressure control means. The control means suppresses the engine rotation speed in response to a request from the engine rotation speed suppression means. By suppressing the amount of heat generated from the V-belt by suppressing an engine speed input, the excessive increase of the continuously variable transmission machine oil temperature can be prevented.

According to a second aspect of the present invention, the failure judging means includes the step of: detecting a failure of the line pressure control means when the line pressure command value is less than a predetermined maximum value and the detected value of the previous line pressure is not less than the predetermined maximum value. , The failure of the line pressure control means can be performed quickly and easily.

In a third aspect of the present invention, the failure determination means is provided after the condition that the line pressure command value is less than a predetermined maximum value and the detected value of the line pressure is not less than a predetermined maximum value continues for a predetermined time. Since the failure of the line pressure control means is determined for the first time, the case where the detected value of the line pressure does not match the command value in a transient state such as a change of the gear ratio is not erroneously determined to be the failure state, and the control accuracy is improved. Can be improved.

According to a fourth aspect of the present invention, the engine control means performs a fuel cut or a reduction in a fuel injection amount so that the engine speed becomes less than a predetermined value in response to a request from the engine speed suppression means. Thus, the engine speed can be reduced, and the amount of heat generated from the V-belt when the line pressure control means fails can be suppressed.

According to a fifth aspect of the present invention, the engine control means reduces the maximum value of the engine speed in response to a request from the engine speed suppression means, thereby preventing the engine speed from becoming a large value. , V when line pressure control means fails
The amount of heat generated from the belt can be suppressed.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a fail-safe control device for a V-belt type continuously variable transmission, FIG. 2 is a longitudinal sectional view of a continuously variable transmission 17, and FIG. FIG.

The continuously variable transmission 17 includes a primary pulley 16 connected to an engine (not shown) as a variable pulley,
There is a secondary pulley 26 connected to the drive shaft, and these variable pulleys are connected by a V-belt 24.

The speed ratio of the continuously variable transmission 17 and the contact frictional force of the V-belt are controlled by a hydraulic control valve 3 having a line pressure solenoid 4 and a step motor 64 responsive to a command from the CVT control unit 1. You.

The CVT control unit 1 includes a primary pulley rotation speed sensor 6 for detecting the rotation speed Npri of the primary pulley 16 of the continuously variable transmission 17 and a secondary pulley rotation speed sensor 7 for detecting the rotation speed Nsec of the secondary pulley 26. Signal and inhibitor switch 8
And a signal from a manual switch (not shown), a throttle opening TVO (or opening of an accelerator pedal) from a throttle opening sensor 5 in accordance with a depression amount of an accelerator pedal operated by a driver, and FIG. The line pressure P detected by the line pressure sensor 70 shown in FIG.
In addition to reading L ′, the engine speed Ne is read from an engine control unit 2 that controls the fuel injection amount, ignition timing, etc. of the engine (not shown). V
The contact frictional force of the belt 24 is variably controlled.

Next, the V-belt type continuously variable transmission 17 will be described with reference to FIG.

A torque converter 12 as a fluid transmission device is connected between an engine output shaft 10 connected to an engine (not shown) and an input shaft 13 of a continuously variable transmission 17. CVT control unit 1 via one hydraulic control valve 3
The lock-up clutch 11 controlled by the

The engine output shaft 10 is connected to a pump impeller 12a, the input shaft 13 of the continuously variable transmission 17 is connected to a turbine runner 12b, and the lock-up clutch 11 selectively connects the pump impeller 12a and the turbine runner 12b. I do.

The input shaft 13 of the continuously variable transmission 17 is connected to a forward / reverse switching mechanism 15 mainly including a planetary gear mechanism 19, and the drive shaft 14 of the planetary gear mechanism 19 is connected to the continuously variable transmission 1.
A primary pulley 16 is provided on the driving side of the motor 7.

The primary pulley 16 includes a fixed conical plate 18 that rotates integrally with the drive shaft 14 and a fixed conical plate 18.
And a movable conical plate 22 that is displaceable in the axial direction of the drive shaft 14 by a hydraulic pressure acting on the primary pulley cylinder chamber 20 (primary pulley hydraulic pressure). The primary pulley cylinder chamber 20 includes oil chambers 20a and 20b, and has a larger pressure receiving area than a secondary pulley cylinder chamber 32 described later.

On the other hand, the secondary pulley 26 is
And a fixed conical plate 30 that rotates integrally with the driven shaft 28, and a V-shaped pulley groove that is disposed opposite to the fixed conical plate 30 to form a secondary pulley cylinder chamber 32. It is composed of a movable conical plate 34 that can be displaced in the axial direction of the driven shaft 28 according to the hydraulic pressure (secondary hydraulic pressure) that acts.

A drive gear 46 meshing with the idler gear 48 is fixed to the driven shaft 28, and a pinion gear 54 provided on the idler shaft 52 of the idler gear 48 is connected to the final gear 4.
4 is engaged. The final gear 44 is a differential gear 5
A drive shaft and a propeller shaft (not shown) are driven via the motor 6.

The driving torque input from the engine output shaft 10 is transmitted to the torque converter 12 and the forward / reverse switching mechanism 15.
When the forward clutch 40 is engaged and the reverse brake 50 is released, the input shaft 1 is transmitted through the planetary gear mechanism 19 which is in an integrally rotating state.
3 is transmitted to the drive shaft 14 in the same rotation direction. On the other hand, when the forward clutch 40 is released and the reverse brake 50 is engaged, the driving torque transmitted to the input shaft 13 by the action of the planetary gear mechanism 19 is in a state where the rotation direction is reversed. The power is transmitted to the drive shaft 14.

The driving torque of the driving shaft 14 is transmitted from the driving gear 46 via the primary pulley 16, the V-belt 24, the secondary pulley 26, and the driven shaft 28 to the idler gear 4.
8, transmitted to the idler shaft 52, the pinion gear 54, and the final gear 44.

In transmitting the driving force as described above, the movable conical plate 22 of the primary pulley 16 and the secondary pulley 2
6 by displacing the movable conical plate 34 in the axial direction,
By changing the contact radius with the pulley 4, the rotation ratio between the primary pulley 1 and the secondary pulley 26, that is, the speed ratio RTO can be changed.

For example, if the width of the V-shaped pulley groove of the primary pulley 16 is reduced, the V
Since the contact radius of the belt 24 becomes large, a large gear ratio can be obtained. If the movable conical plates 22 and 34 are displaced in the opposite direction, the gear ratio becomes smaller.

The control for changing the widths of the V-shaped pulley grooves of the primary pulley 16 and the secondary pulley 26 is performed by hydraulic control of the primary pulley cylinder chamber 20 and the secondary pulley cylinder chamber 32.

The hydraulic control is performed by controlling the line pressure solenoid 4 of the hydraulic control valve 3 and the step motor 64 as shown in FIG.

First, the line pressure control system for adjusting the contact friction force of the V-belt 24 is mainly composed of a line pressure solenoid 4, and this line pressure solenoid 4 employs a normal apply which opens when the power is cut off. Then, the duty is controlled by a command signal from the CVT control unit 1. Then, by making the line pressure solenoid 4 a normal apply, a fail-safe means for supplying the maximum line pressure when the power supply is cut off is configured.

The duty control of the line pressure is the same as in Japanese Patent Application No. 8-31954 proposed by the present applicant, and the throttle opening TVO (or accelerator pedal opening) and the engine speed Ne are controlled. From the input torque Tin of the continuously variable transmission 17 estimated on the basis of the engine torque Te ′ estimated from the line pressure, the line pressure command value PL is obtained, and the line pressure solenoid is provided at a duty ratio corresponding to the obtained line pressure command value PL. 4 is driven.

The line pressure solenoid 4 drains the oil pressure Pb from the pressure modifier 62 to the pilot valve 61 as the oil pressure Pc in accordance with the duty ratio from the CVT control unit 1, and the line pressure regulator 60 A line pressure P corresponding to the hydraulic pressure Pc applied to the pilot valve 61
It is set to L.

On the other hand, the gear ratio RTO of the primary pulley 16 and the secondary pulley 26 is controlled by a step motor 64 driven according to a shift command signal from the CVT control unit 1, and a shift control is performed according to the displacement of the step motor 64. The valve 63 is driven, and the hydraulic pressure supplied to the cylinder chamber 20 of the primary pulley 16 is adjusted to set a predetermined gear ratio RTO.

The line pressure sensor 70 for detecting the line pressure includes a line pressure regulator 60 and a shift control valve 63.
And the detected value PL 'is interposed in the line pressure circuit
Send to T control unit 1.

Next, an example of hydraulic control performed by the CVT control unit 1 will be described in detail with reference to the flowchart of FIG. Note that the flowchart of FIG. 4 is performed every predetermined time, for example, every several tens msec.

In step S1, the line pressure command value PL obtained by the above line pressure control and the detected line pressure PL 'of the line pressure sensor 70 are read, and in steps S2 and S3, the two data PL and PL' are The failure determination of the line pressure control system is performed based on the determination.

In step S2, it is determined whether the line pressure command value PL is less than the maximum value PLmax. If it is less than the maximum value PLmax, the detection value P of the line pressure sensor 70 is determined in step S3.
It is determined whether L ′ is equal to or greater than the maximum value PLmax, and the command value P
If the detected value PL 'is equal to or greater than the maximum value PLmax when L is less than the maximum value PLmax, the line pressure control system fails, the line pressure solenoid 4 is de-energized, and the valve is continuously opened. And the process proceeds to step S4.

If it is determined in steps S2 and S3 that the condition is NO, the process proceeds to step S10, where the control flag F indicating a fault condition is reset to 0, and the process ends.

In step S4, it is determined whether or not the control flag F indicating the failure state is 1, that is, whether or not the state is a failure state. If F = 1, the control for suppressing the engine speed after step S5 is performed. In the first loop, the process proceeds to step S9 to reset the timer Timer and set the control flag F to 1 to end the process.

Then, after the control flag F = 1, 2
In the second loop, the process proceeds to step S5, where the timer Ti
mer is incremented, and in step S6, the timer Ti
It is determined whether mer has passed a predetermined time Time1.

When a predetermined time Time1 has elapsed since the failure was determined and the control flag was set to 1, step S7
And a rotation speed command signal FN preset to a predetermined rotation speed.
After e is transmitted to the engine control unit 2, the control flag F is reset in step S8, and the process is terminated.

In this manner, the rotational speed command signal FNe to the engine control unit 2 is maintained until the predetermined time Time1 elapses after the failure state of the line pressure control system is determined.
When the transmission control valve 63 or the like is driven to change the gear ratio, the detection value PL 'is transiently detected.
Is fluctuated and does not coincide with the command value PL, it is prevented from being determined as a failure state, and the failure state of the line pressure control system is accurately determined.

On the other hand, an example of the engine speed control performed by the engine control unit 2 based on the speed command signal FNe from the CVT control unit 2 will be described.
This will be described in detail with reference to the flowchart of FIG. In addition,
This flowchart is also executed at predetermined time intervals in the same manner as described above.

First, at step S10, the rotational speed command signal FNe from the CVT control unit 2 is read, and then at step S11, the current engine rotational speed Ne is compared with the rotational speed command signal FNe.

If the current engine speed Ne is equal to or higher than the value set by the speed command signal FNe, step S1 is executed.
The control proceeds to 2 to cut or reduce the fuel injection amount, and control is performed such that the engine speed Ne becomes equal to or lower than the speed command signal FNe.

With the above control, when the line pressure control system fails and the line pressure solenoid 4 is opened, the oil pressure Pb of the pressure modifier 62 becomes the oil pressure Pc of the pilot valve 61 as it is as described above. , The line pressure rises to almost the maximum value PLmax, and the primary pulley 16, the secondary pulley 26 and the V belt 24
To prevent the slippage of the V-belt 24 and reliably transmit the driving force of the engine to the drive shaft, thereby ensuring the running of the vehicle.

If the vehicle continues to travel with the line pressure at the maximum value PLmax, as described above, heat is generated from the V-belt 24, the primary pulley 16, and the secondary pulley 26 due to the increased contact frictional force.
Increase of the oil temperature T becomes excessive.

Here, according to an experiment conducted by the applicant of the present invention, the amount of heat generated when the line pressure is close to the maximum value PLmax increases the oil temperature T according to the input rotation speed, that is, the engine rotation speed Ne. Make sure you do.

Therefore, the CVT control unit 2
Detects a failure in the line pressure control system, requests the engine control unit 2 to reduce the engine speed to a predetermined value FNe,
In response to this, the line pressure is substantially increased to the maximum value PLma in order to cut the fuel or reduce the fuel injection amount so that the engine speed Ne becomes the new target engine speed NFe.
By setting the value x, the engine speed Ne is suppressed to a predetermined value or less while the slippage of the V-belt 24 is prevented and the running of the vehicle is ensured. Oil temperature T can be prevented from increasing excessively, and the vehicle can run even if the line pressure control system breaks down without reducing the durability of the continuously variable transmission 17. It is.

FIG. 6 shows a second embodiment, in which the first embodiment is used.
In the embodiment, the rotation speed command signal NFe sent from the CVT control unit 2 is set to a flag represented by ON and OFF, and the engine control unit 2 calculates the engine rotation speed when the rotation speed command signal NFe is turned ON. change maximum Nemax to the normal maximum value N ₀ is smaller than a predetermined value N _1, and the like in the same manner as described above in a fuel cut or the fuel injection quantity reduced, the new engine speed maximum value N ₁
Is controlled so as not to exceed, and the others are the same as in the first embodiment.

Also in this case, the power transmission is reliably performed by the maximum value PLmax of the line pressure while suppressing the heat generation of the V-belt 24 to prevent the oil temperature T of the continuously variable transmission 17 from excessively increasing, thereby ensuring the line pressure. When the control system fails, the vehicle can continue running without reducing the durability of the continuously variable transmission 17.

In the above embodiment, the case where the fuel injection amount is controlled is shown as a means for reducing the engine speed Ne. However, in the spark ignition type engine, the ignition timing is retarded and the second throttle driven by the actuator is controlled. For example, the engine speed may be suppressed.

[0061]

As described above, according to the first aspect, in the event that the line pressure control means fails, first, the fail-safe means supplies a predetermined maximum oil pressure to the variable pulley. The running of the vehicle can be continued by preventing the belt from slipping.At this time, since the detected value of the line pressure does not match the line pressure command value from the shift control means due to the failure, the failure determination means determines that the line pressure control means has failed. The engine control means suppresses the engine speed in response to the request from the engine speed suppression means, and the contact friction force of the V-belt is increased by the maximum hydraulic pressure. By controlling the engine speed
By suppressing the amount of heat generated from the belt, it is possible to prevent the oil temperature in the continuously variable transmission from rising excessively, and to improve the durability of the continuously variable transmission while enabling running when the line pressure control system fails. It is possible to secure.

According to a second aspect of the present invention, the failure judging means includes a step of detecting a failure of the line pressure control means when the line pressure command value is less than a predetermined maximum value and the detected value of the previous line pressure is not less than the predetermined maximum value. , The failure of the line pressure control system can be performed quickly and easily.

According to a third aspect of the present invention, the failure determination means is provided after the state in which the line pressure command value is less than a predetermined maximum value and the detected line pressure value is equal to or more than a predetermined maximum value continues for a predetermined time. Since the failure of the line pressure control means is determined for the first time, the case where the detected value of the line pressure does not match the command value in a transient state such as a change of the gear ratio is not erroneously determined to be the failure state, and the line pressure control is not performed. It is possible to accurately determine a system failure and improve control accuracy.

According to a fourth aspect of the present invention, the engine control means performs a fuel cut or a reduction in a fuel injection amount such that the engine speed becomes less than a predetermined value in response to a request from the engine speed suppression means. As a result, the engine speed can be reduced, the amount of heat generated from the V-belt when the line pressure control means fails, and the durability of the continuously variable transmission is ensured while enabling running when the line pressure control system fails. It is possible to do.

In the fifth invention, the engine control means reduces the maximum value of the engine speed in response to a request from the engine speed suppression means, thereby preventing the engine speed from becoming a large value. , V when line pressure control means fails
The amount of heat generated from the belt can be suppressed, and the durability of the continuously variable transmission can be ensured while enabling running when the line pressure control system has failed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view of the continuously variable transmission.

FIG. 3 is a schematic diagram of the hydraulic control valve.

FIG. 4 is a flowchart performed by the CVT control unit at predetermined time intervals, showing an example of a line pressure control system failure process.

FIG. 5 is a flowchart performed by the engine control unit at predetermined time intervals, showing an example of engine speed suppression control.

FIG. 6 shows another embodiment, and shows an example of maximum rotation speed control in a flowchart performed at predetermined time intervals by an engine control unit.

FIG. 7 is a graph showing the relationship between the line pressure and the oil temperature, showing a case where the gear ratio RTO and the number of revolutions are constant.

FIG. 8 is a diagram corresponding to claims corresponding to the first to fifth inventions.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CVT control unit 2 Engine control unit 3 Hydraulic control valve 4 Line pressure solenoid 5 Throttle opening sensor 6 Primary speed sensor 7 Secondary speed sensor 8 Inhibitor switch 16 Primary pulley 17 Continuously variable transmission 18 Fixed conical plate 19 Planetary gear mechanism Reference Signs List 20 primary pulley cylinder chamber 22 movable conical plate 24 V belt 26 secondary pulley 28 driven shaft 30 fixed conical plate 32 secondary pulley cylinder chamber 34 movable conical plate 60 line pressure regulator 63 shift control valve 64 step motor 70 line pressure sensor 100 stepless speed change Machine 101 shift control means 102 engine control means 103 hydraulic control means 104 hydraulic correction means 105 shift mode switching means

Continuation of front page (56) References JP-A-1-116364 (JP, A) JP-A-57-161346 (JP, A) JP-A-61-105347 (JP, A) JP-A-62-139730 (JP, A) JP-A-1-95943 (JP, A) JP-A-7-77079 (JP, A) JP-A-62-52260 (JP, A) JP-A-5-104989 (JP, A) 62-53251 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 29/00 F02D 41/00-45/00 B60K 41/00 F16H 9/00 F16H 61/00

Claims (5)

(57) [Claims] 1. A continuously variable transmission having a pair of variable pulleys on a primary side and a secondary side in which a contact frictional force of a V-belt is variably controlled based on a line pressure, and the line pressure according to a driving state of a vehicle. Shift control means for calculating the command value of: line pressure control means for adjusting the oil pressure from a hydraulic pressure source based on the line pressure command value and supplying the variable pressure to the variable pulley; and Is a fail-safe control device for a continuously variable transmission having a fail-safe means for supplying a predetermined maximum line pressure to the variable pulley. The fail-safe control device controls an engine connected to the continuously variable transmission according to a driving state of a vehicle. An engine control means for detecting the line pressure; a means for detecting the line pressure; and a line pressure control means based on a detected value of the line pressure and a line pressure command value of the shift control means. Failure determination means for determining a failure; and engine rotation speed suppression means for requesting the engine control means to reduce the engine rotation speed when the failure is determined in the determination, wherein the engine control means suppresses the engine rotation speed. A fail-safe control apparatus for a continuously variable transmission, wherein the engine speed is suppressed in response to a request from the means. 2. The failure determination means determines that the line pressure control means determines a failure when the line pressure command value is less than a predetermined maximum value and the detected value of the line pressure is not less than a predetermined maximum value. The fail-safe control apparatus for a continuously variable transmission according to claim 1, wherein: 3. The line pressure control unit according to claim 1, wherein the line pressure command value is less than a predetermined maximum value and the line pressure detection value is equal to or greater than a predetermined maximum value for a predetermined time. The fail-safe control apparatus for a continuously variable transmission according to claim 1, wherein the failure is determined. 4. The fuel supply system according to claim 1, wherein the engine control means performs a fuel cut or a fuel injection amount reduction according to a request from the engine speed suppression means so that the engine speed becomes less than a predetermined value. Item 2. A fail-safe control device for a continuously variable transmission according to item 1. 5. The fail-safe control of a continuously variable transmission according to claim 1, wherein said engine control means reduces the maximum value of the engine speed in response to a request from the engine speed suppression means. apparatus.